1. Field of the Invention
This invention pertains to a donor element for use with a receiver element in an imageable assemblage for light-induced transfer of material from the donor element to the receiver element.
2. Description of Related Art
Donor elements for use with a receiver element in an imageable assemblage for light induced transfer of material from the donor element to the receiver element typically include multiple layers. The layers can include but are not limited to a support layer, a light-to-heat conversion (LTHC) layer, and a transfer layer. Typically a support layer such as a 50 μm polyethylene terephthalate film is sequentially coated with a LTHC layer precursor, the precursor is converted to a final LTHC layer by drying, and subsequently a transfer layer precursor is coated above the LTHC layer opposite the support layer and converted to a transfer layer by drying.
Materials can be selectively thermally transferred to form elements useful in electronic displays and other devices and objects. Specifically, selective thermal transfer of color filters, spacers, polarizers, conductive layers, transistors, phosphors and organic electroluminescent materials have all been proposed. Materials such as colorants can be selectively thermally transferred to form objects such as a proof copy of a reference image.
There remains a need for improvements in thermal transfer imaging donor elements in the effectiveness and selectivity of moving transferable material from a donor element, and in the effectiveness and selectivity of depositing and adhering and fixing transferred material to a receiver. Improvements in thermal transfer imaging donor elements that decrease unintended transfer of layers to a receiver element are sought. Improvements in thermal transfer imaging donor elements that improve the handling characteristics and damage resistance of the donor element are sought.
There remains a need for improvements to thermal transfer donor elements and improvements in their use with receiver elements in an imageable assemblage, in order to improve at least one of thermal transfer efficiency, independence of thermal transfer efficiency from any variation of heating, independence of thermal transfer efficiency from any variation of environmental conditions such as humidity and temperature, completeness of mass transfer, freedom from unintended mass transfer, clean separation of mass transferred and unimaged regions of the donor, and smoothness of the surface and edges of mass transferred material.
Films such as polyethylene terephthalate have long been coated with materials such as antistats and adhesion modifiers. There is a continuing need for improvements of formulations in this area to provide films with improved properties and utility.
Examples of known donor elements and their conventional use are described by U.S. Pat. No. 6,485,884 (Wolk, et al.) and U.S. Pat. No. 6,146,792 (Blanchet-Fincher, et al.).
U.S. Pat. No. 6,485,884 of Wolk, et al. provides a method for patterning oriented materials to make organic electronic displays or devices. The method includes selective thermal transfer of an oriented electronically active or emissive material from a thermal transfer donor sheet to a receptor. One method for providing an oriented light emitting polymer transfer layer is to coat an orientable light emitting polymer onto a donor sheet and to stretch the resulting transfer sheet in an orientation direction. In this method, the orientable light emitting polymer can be solubilized by addition of a suitable compatible solvent, and coated onto the donor sheet by spin-coating, gravure coating, mayer rod coating, knife coating and the like. The solvent chosen preferably does not undesirably interact with (e.g., swell or dissolve) any of the already existing layers in the donor sheet. The solvent can then be evaporated from the coating to make a fully formed donor sheet. The donor sheet can then be stretched or tentered in a selected direction to align the molecules of the orientable material of the transfer layer. This method may be suited to lamination transfer methods where an orientable transfer layer is coated onto a donor substrate, the composite article is stretched or tentered to orient the orientable transfer layer, and the transfer layer is transferred in its oriented state to a receptor by applying heat and/or pressure. In this way, the entire transfer layer, or large portion thereof, can be transferred in one exposure.
U.S. Pat. No. 6,146,792 of Blanchet-Fincher, et al. discloses donor elements comprising an ejection layer, a heating layer, and a transfer layer. The ejection layer can have additives, as long as they do not interfere with the essential function of the layer. Examples of such additives include coating aids, flow additives, slip agents, antihalation agents, antistatic agents, surfactants, and others which are known to be used in formulation of coatings.